1. Field of Technology
The present invention relates to a sheet finisher to be connected to an image forming apparatus, an image forming apparatus to which the sheet finisher is connected and an image forming system to which the image forming apparatus and the sheet finisher are connected. In particular, the invention relates to those each being one wherein an image-reading section is provided on the sheet finisher.
2. Description of Related Art
The sheet finisher having therein an image-reading section is proposed in each of official reports of Unexamined Japanese Patent Application Publication No. 2003-110806 and Unexamined Japanese Patent Application Publication No. 2007-97083.
In the image forming system described in Unexamined Japanese Patent Application Publication No. 2003-110806, image data which are acquired through reading by an image-reading section provided on the sheet finisher are used for correction of image forming conditions in image forming that is practiced by an image forming apparatus, and an image is formed by the image forming apparatus based on the image data acquired by reading by the image-reading section.
In the technology in Unexamined Japanese Patent Application Publication No. 2007-97083, timing control for controlling timing scanning control representing image-reading control and sheet finishing control is carried out for conducting image-reading effectively in the sheet finisher.
As is described in Unexamined Japanese Patent Application Publication No. 2003-110806 and Unexamined Japanese Patent Application Publication No. 2007-97083, image data generated through image-reading by the image reading section in the sheet finisher are transmitted to the image forming apparatus, to be used in the image forming apparatus.
The image forming apparatus and the sheet finisher are connected by an ordinary communication device, and transmission and reception of control data are carried out through the communication device, and when image data are transmitted or received by the aforesaid communication device, following problems are caused.
An amount of data of image data is remarkably large when it is compared with an amount of data of control data for sheet finishing. For this reason, communication for image data takes a long time, and if communication of image data is conducted in a job, communication of control data and communication of image data conflict with each other, and there is sometimes an occasion that results in inability to operate and in suspension of the system.
In Unexamined Japanese Patent Application Publication No. 2007-97083, image reading is made to be more effective through timing control for image-reading control (scanning control) in the sheet finisher and in sheet finishing control. However, in Unexamined Japanese Patent Application Publication No. 2007-97083, a period of time for transmission of image data is not considered at all. Therefore, when practicing the timing control mentioned in Unexamined Japanese Patent Application Publication No. 2007-97083, there is caused sometimes an occasion wherein the system does not work normally because of the causes which were explained earlier.
For the communication of control data for sheet finishing, there has been used communication wire employing a communication cable has been used. However, the aforesaid difficulties cannot be avoided in the communication system that is designed for the control of this kind. In this case, utilization of a high speed communication device capable of dealing with image data is considered, which, however has a problem of cost increase. Further, when adding an image-reading function to the image system by using an existing image forming system, it is necessary to provide a high speed communication device in addition to the image reading section, which results in a large increase in cost.